#VU18686 OS Command Injection in Exim - CVE-2019-10149

Vulnerability identifier: #VU18686

Vulnerability risk: High

CVSSv4.0: 9.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:A/U:Amber]

CVE-ID: CVE-2019-10149

CWE-ID: CWE-78

Exploitation vector: Network

Exploit availability: Yes

Vulnerable software:
Exim
Server applications / Mail servers

Vendor: Exim

Description

The vulnerability allows a remote attacker to execute arbitrary shell commands on the target system.

The vulnerability exists due to insufficient validation of email address within the deliver_message() function in /src/deliver.c. A remote unauthenticated attacker can send an email containing a specially crafted email address and execute arbitrary OS commands on the target system via execv() call with superuser privileges.

This vulnerability can be also exploited by authenticated local users to escalate privileges on the system.

Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Exim: 4.87 - 4.91

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External links
https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2019-10149
https://www.exim.org/static/doc/security/CVE-2019-10149.txt
https://www.qualys.com/2019/06/05/cve-2019-10149/return-wizard-rce-exim-abridged.txt

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

Yes. This vulnerability is being exploited in the wild.